1. Field of the Invention
The invention relates to a method and an electrode assembly for the consumable electrode vacuum arc melting of metals and alloys, particularly reactive metals and alloys of titanium.
2. Description of the Prior Art
In the production of metals and alloys, and particularly reactive metals and alloys of titanium, it is known to produce the same by consumable electrode, vacuum arc melting.
In this practice an electrode is made of the material to be melted and refined. The electrode is placed in a water cooled, evacuated mold and electric current is passed through the electrode and mold to create an arc between the electrode and the mold to produce progressive melting away of the electrode material into the mold. During this operation the mold is continuously evacuated to remove the impurities released as gaseous reaction products during the melting operation. As the electrode is melted it progressively solidifies in the mold to form a solidified ingot therein.
As the melting of the electrode nears completion, it is conventional practice to leave a portion of the electrode unmelted. Otherwise, melting of the electrode holder and thus contamination of the alloy of the ingot may result. This unmelted material is then recycled for further electrode production and subsequent melting. This results in a significant production cost increase resulting from the required remelting. For example, in a conventional triple-vacuum arc melting operation of a conventional alloy of Ti-6 Al-4V alloy, the unmelted electrode portion from the second and final melt will typically weigh 300 to 500 pounds each, thus resulting in a recycled material weight of 600 to 100 pounds.